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Site History
<br /> Boyett Petroleum(419 S. Main St.,Manteca)
<br /> Page 8 of 10
<br /> Condor conducted monitoring well destruction and installation activities at the site on October 29 and 30,
<br /> 2003. The work was performed in general accordance with the Interim Remediation Work Plan, dated
<br /> June 25, 2003. On October 29, 2003, Condor supervised the destruction of monitoring wells MW-1,
<br /> MW-4, and MW-5. The monitoring wells were destroyed by over drilling the wells with 8-inch outside
<br /> diameter, continuous-flight, hollow-stem auger and removing all well construction materials. On October
<br /> 30, 2003, three four-inch diameter groundwater monitoring wells (MW-4R, MW-10, and MW-11) and
<br /> one four-inch diameter extraction well (EW-1) were installed. Soil grab samples were collected from each
<br /> monitoring/extraction well boring for laboratory analyses to characterize the soil for disposal. Laboratory
<br /> analytical results indicated that BTEX, gasoline oxygenates/additives other than MTBE, and TPH-G were
<br /> not detected at or above the laboratory reported detection limits in the soil samples collected from the
<br /> borings for MW-4R, MW-10, MW-11, and EW-1. MTBE was detected in soil samples collected from
<br /> wells MW-11 and EW-1. Lead was detected in soil samples collected from wells MW-4R, MW-10, and
<br /> MW-11. The October 2003 monitoring well destruction and installation activities were described in
<br /> Condor's Additional Groundwater Investigation, Monitor Well Destruction and Installation, and Interim
<br /> Remediation Pump Test Report, dated January 30, 2004.
<br /> On October 31, 2003, a Condor representative was on site to measure water levels and collect
<br /> groundwater samples for MTBE laboratory analysis from monitoring wells MW-2, MW-3, MW-6, MW-
<br /> 7, MW-8, and MW-9. Monitoring wells MW-2, MW-6, and MW-7 were dry, and monitoring wells MW-
<br /> 3 and MW-8 purged dry; as a result, a groundwater sample was collected only from monitoring well MW-
<br /> 9. At the time of the October 2003 monitoring event, MW-4R, MW-10, MW-22, and EW-1 had not yet
<br /> been developed; thus, monthly monitoring activities were not conducted at these wells. Laboratory
<br /> analytical results for the groundwater sample collected from MW-9 indicated that BTEX, gasoline
<br /> oxygenates/additives other than MTBE, and TPH-G were not detected at or above the laboratory reported
<br /> detection limits. MTBE was detected in the groundwater sample collected from MW-9. Depth to
<br /> groundwater measurements,relative to MW-3, MW-8, and MW-9, indicated that the average groundwater
<br /> elevation decreased with respect to the previous monitoring event.
<br /> On November 5, 2003, wells MW-4R, MW-10, MW-11, and EW-1 were surveyed to determine the
<br /> location and elevation of the well collars relative to a NAVD88 benchmark datum (Benchmark No.
<br /> HS4486).
<br /> On November 14, 2003, wells EW-1 and MW-11 were developed by surging and bailing the groundwater
<br /> in the wells with a surge block and disposable, polyethylene bailers. MW-4R and MW-10 were dry. A
<br /> total of ten well-bore volumes were removed from each well during development. No floating product or
<br /> sheen was observed and no petroleum hydrocarbon odors were noted in the groundwater purged from
<br /> either EW-1 or MW-11 during development.
<br /> From November 18 through 21, 2003, Condor conducted a 72-hour constant rate pump test at well MW-
<br /> 11. During the pump test, observations of the head pressure response were electronically recorded with
<br /> transducers placed in EW-1, MW-9, and MW-11. Groundwater pumped from MW-11 was treated by
<br /> passing the water through coconut shell granulated activated carbon canisters prior to discharge to the
<br /> City of Manteca sanitary sewer system. Four water samples were collected during the pump test: two at
<br /> the beginning and two at the end. Samples were collected from the influent port before the carbon
<br /> canisters and from the discharge port after the carbon canisters following on-site treatment.
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<br /> analytical results indicated that the treated groundwater met the requirements aof the City of Manteca
<br /> Industrial Wastewater Discharge Permit (IWDP) disposal requirements. Pump test activities were
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